Obstructive sleep apnea in middle-aged adults may increase the risk of
coronary artery disease by up to five-fold, research in Sweden suggests.
However, successful treatment of the sleep apnea significantly cuts that
risk.
Although evidence supports ties between sleep apnea -- that is, brief but
frequent episodes during the night when breathing becomes blocked -- and
coronary artery disease, a causal relationship has not been established, Dr.
Yuksel Peker and his colleagues at Sahlgrenska University Hospital in Goteborg
note. The concomitant presence of other illnesses further complicates the
ability to delineate cause and effect.
For their study, Peker's team identified 308 middle-age individuals (ages 30
to 69 years) who had been evaluated for obstructive sleep apnea in 1991 and were
free of any heart disease at baseline. Nearly one-third (n=105) patients had
documented obstructive sleep apnea.
Patients were offered various standard treatments including CPAP (continuous
positive airway pressure), surgery, or an oral appliance. Sleep apnea was not
resolved despite treatment or offers of treatment in 65 patients.
Over the next 7 years, coronary artery disease was diagnosed in 16.2 percent
of patients with sleep apnea and 5.4 percent of those without apnea. Eight
deaths due to coronary artery disease occurred in the apnea group and one in the
non-apnea group.
Among patients with ineffective treatment, coronary artery disease was
diagnosed in 24.6 percent versus 3.9 percent of those effectively treated.
In "multivariate analysis," obstructive sleep apnea at baseline nearly
quintupled the risk of developing coronary artery disease, the investigators
report, regardless of age, gender, high blood pressure, diabetes, or current
smoking.
However, effective sleep apnea treatment reduced the increased risk by about
two thirds.
In the European Respiratory Journal, Peker's team maintains that their study
"clearly suggests a causal relationship between obstructive sleep apnea and
coronary artery disease."
"Even mild obstructive sleep apnea seems to have a substantial effect on
coronary artery disease risk, and highly effective treatment should therefore be
provided," they write.
